Long description for example showing how structurally
overlapping cells are rendered

This example shows two different ways to render tables that are
defined by HTML (and thus XHTML1) to be illegal, because of their
specific combination of rowspan and colspan attributes.

The rendering on the left has two cells that overlap. The rendering
on the right doesn't, but leaves a gap in the table.

In both tables, cells have gray backgrounds and a black
border. Each contains a single digit as label. Cells are separated
from each other by cell spacing.

The left table has a top row of four cells, containing, resp. the
digits "1", "2", "3", and "4". The second of these cells, the one with
the digit "2" in it, extends into the row below. The second row of the
table contains one cell, which contains the digit "5", and it spans
columns one and two. Thus, the cell labeled "2" and the cell labeled
"5" overlap in the second row, second column. The overlap is depicted
by a darker gray background.

The right table has the same top row of four cells, labeled "1",
"2", "3", and "4". The second cell again spans rows one and two. The
second row of the table contains one cell, containing the digit "5",
that spans columns three and four. Thus, no cells overlap, but the
first cell of the second row is left empty.